Messages in this thread | | | Date | Fri, 22 Oct 2010 10:36:57 -0400 | From | Jason Baron <> | Subject | Re: [PATCH][GIT PULL] tracing: Fix compile issue for trace_sched_wakeup.c |
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On Fri, Oct 22, 2010 at 04:23:02PM +0200, Peter Zijlstra wrote: > On Fri, 2010-10-22 at 10:13 -0400, Jason Baron wrote: > > On Fri, Oct 22, 2010 at 10:14:31AM +0200, Peter Zijlstra wrote: > > > On Thu, 2010-10-21 at 21:44 -0400, Jason Baron wrote: > > > > > > > I finally found that we actually continue to run after the above > > > > apparent 'hang'. That is, we continue to make progress updating the jump > > > > labels. And doing a dump of all the system tasks at the time of the hang > > > > showed the processes in various places besides the stop machine threads. > > > > Thus, I thought that perhaps, for some reason the stop machine threads > > > > weren't being scheduled. > > > > > > > > Thus, I tried commenting out the special scheduling that is set up for > > > > stop machine threads, and that fixed the hang. I haven't yet looked into > > > > what might be going wrong with that scheduling...but maybe somebody else > > > > knows... > > > > > > Hrmm, so are you saying rq->stop was runnable but not running? > > > > yes, that's what it seems like. > > > > > > > > That would imply broken wakeup-preemption, does something like the below > > > cure that? > > > > > > > > > > no still seeing the same hang with the below patch...also, as a data point I > > backed out the patch that adds the stop_sched_class and that resolved the hang > > as well - just as a data point. > > Weird... and there's no hotplugging happening, right? >
don't think so.
> Can this be reproduced in qemu? I don't have a i386-smp machine around > to use. >
its actually an amd 64-bit system with a 32-bit install of f13...
> Could you trace the thing with all sched (except the sched_stat) > tracepoints enabled? I think there's a sysrq key to dump the trace once > the machine's stuck.. >
the current test is triguring this on boot testing enabling/disabling the tracepoints...so it would be interesting to disable the boot test, and see if I can re-produce it at run-time...which will make getting the trace much easier :)
-Jason
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